Aldehydes, particularly formaldehyde and glutaraldehyde, are classical disinfectants, sterilizing and preserving agents used since the 18th Century. Formaldehyde is used by health care institutions for preserving tissue and by industry for various manufacturing processes including paper processing and textile treatments. Formaldehyde is also used in the funeral home business for embalming and for disinfecting the surrounding work areas. Formaldehyde, also referred to as "formalin", is sold to these institutions both in a concentrated form (37 to 50% formaldehyde, 6 to 15% alcohol stabilizer, and water) and in dilution, the most common concentration being 3.75% formaldehyde or 10% formalin.
Glutaraldehydes are used by hospitals and laboratories as cold sterilant solutions. The major difference between glutaraldehyde and formaldehyde is that each molecule of glutaraldehyde has five carbons and two reactive carbonyl groups, while formaldehyde has only one carbon and one carbonyl group and is of a lower molecular weight. "Formalin" most likely exists as the "hemiacetal" in alcoholic water solutions in equilibrium. ##STR1## are the only chemicals approved by the EPA as a cold sterilant for sterilizing surgical instruments, endoscopic equipment, arthroscopic instruments, cameras, and similar medical apparatus. Glutaraldehyde is also used to sterilize other surgical instruments and supplies that may be damaged by other sterilizing methods such as steam autoclaving and ethylene oxide (ETO).
The use of aldehydes for medical and industrial applications is extensive. There are millions of gallons of waste water disposed of each year that are contaminated by "aldehyde" solutions. Many aldehydes are classified as acutely-toxic by the EPA. Their use and disposal are regulated by the Food and Drug Administration (FDA), the Occupational Safety and Health Agency (OSHA), the Environmental Protection Agency (EPA), and other state, county and city health and environmental resource departments and Publicly Owned Treatment Works (POTWs). Aldehydes are a particularly insidious danger to the POTWs because they are not detected at levels that are toxic to E. coli in the sludge and cause "pass through" after killing the sludge at 0.2 to 1.0 ppm concentrations.
Aldehydes are particularly useful in pathological, biological, microbiological and dissecting laboratories because of their quick, effective kill of all pathogenic organisms. However, aldehydes, with their carbonyl groups, are carcinogenic to mammals. Increasing concern for worker exposure and the environment have initiated the development of new handling, storage, and disposal regulations to limit worker and public exposure. The OSHA defined exposure limit for formaldehyde is 0.75 ppm for an eight-hour exposure period; beyond this level a respirator must be used. Even at this low level of concentration, formaldehyde may not be generally detectable to the sense of smell. If the aldehyde can be smelled,the concentration probably exceeds OSHA Exposure Limits and safety standards.
The risks associated with handling aldehydes begins for the user with the storage of the concentrate after arrival at the purchaser's facility. It continues when the concentrate is diluted for use in the laboratory, operating room, emergency room, morgue and other areas; and finally, when the contaminated "waste water" is collected at the point-of-use. Health risks for workers continue as the used material, typically 10% formalin (3.75% formaldehyde), is transported to designated storage areas or poured down the drain into waste water treatment systems. Disposal of aldehydes is regulated by the local publicly owned waste water treatment system (POTW).
All pollutants and pesticides are considered to be a threat to microbes that are needed to break down waste materials in the Waste water treatment process. New regulations are designed to prevent the waste generator from disposing of toxic materials into the POTW. The local POTW has the authority to monitor waste water at the generation site. Hospitals, laboratories, funeral homes and industry are now held to a much higher standard of control and compliance than they were a few years ago. The liability exposure is considerable to violators, both to their reputation in the community and to the possibility of substantial fines for each violation.
The highest levels of formalin sold for cold sterilization and for preserving tissue range from 37 to 50% active formaldehyde. Concentrations in this range must be disposed by a licensed hazardous waste disposal facility. In essence, formaldehyde at these concentrations must be either incinerated or recycled. Lower concentrations of formaldehyde must be handled in a similar way. Many hazardous and toxic waste contractors pour the contaminated waste water into absorbents, such as vermiculite, to convert this into a "solid", thereby making it possible to burn the material in the more numerous solid hazardous waste incinerators. However, this "pouring" and "handling" increases the facility employees' exposure to these toxic materials.
As concern for worker and environmental exposure increases, various methods, techniques and products have been sought to reduce the risk of exposure to these potentially toxic and carcinogenic aldehydes. However, to date, there has not been a suitable and cost effective method available to remove aldehydes such as formaldehyde and glutaraldehyde from waste streams after their disinfecting properties have been utilized.
It is an object of the present invention to provide a method of removing spent aldehydes from liquids, with the residual material being substantially non-toxic which can then be safely and efficiently disposed in the sewer.
An additional objective of the present invention is to convert a toxic composition containing an aldehyde, such as formaldehyde or glutaraldehyde, to a non-toxic composition by a substantially irreversible reaction.
These and further objects will be more readily appreciated when considering the following disclosure and appended claims.